When a host vehicle is being driven in an automated or autonomous driving mode, it may be helpful to have data relating to stationary roadside objects, like guardrails or barriers. Such data not only informs the host vehicle of the presence of the stationary objects, it may also provide the host vehicle with information on the road or drivable area, as such stationary objects oftentimes follow the path of the road itself. Because of the large amount of data that can be generated by vehicle mounted sensors, such as multiple forward looking radar sensors, it may be helpful for the host vehicle to filter or reduce the sensor data before applying it to data fitting algorithms or the like.